The present invention relates to a method of hydrocracking of hydrocarbon oils, and a catalyst that is suitable for hydrocracking of hydrocarbon oils and a method of its production. The present invention particularly relates to a method of hydrocracking with which the vacuum gas oil fractions can be efficiently converted to light gas oil by hydrocracking, as well as a catalyst that is suitable for hydrocracking of the vacuum gas oil fractions and a method of its production.
The demand for oil has recently shifted toward gas oils. Although gasoline and naphtha can be mass-produced by fluidized catalytic cracking, kerosene, gas oil, jet fuel, etc., which are referred to as middle distillates, of preferred quality are not obtained by fluidized catalytic cracking. Therefore, the method of hydrocracking of vacuum gas oil is often used for mass-production of high-quality middle distillates in the oil refining industry.
Although the desired fraction can be obtained by bringing the crude oil and catalyst into contact at a high temperature in the presence of hydrogen under high pressure in the field of hydrocracking of vacuum gas oil, selection of the reaction conditions and catalyst for this is important. For example, more severe reaction conditions or a catalyst of a hydrogenation active metal species supported on a carrier with a higher content of solid, strongly acidic zeolite can be used in order to improve the conversion rate. Nevertheless, when a reaction is performed using this type of catalyst, there is a disadvantage in that although the conversion rate is increased, large quantities of gas and naphtha are produced and selectivity of the middle distillates therefore is poor.
Therefore, taking into consideration diffusibility of the hydrocarbon molecules that will react, attention is given to the fine pore distribution of the catalyst in designs of catalysts that efficiently produce middle distillate (Julius Scherzer, A. J. Gruia, xe2x80x98Hydrocracking Science and Technology,xe2x80x99 Mercel Dekker, Inc., New York, 1996). For instance, Japanese Patent Application Laid Open No. 06-190278 discloses that a hydrocracking catalyst of a hydrogenation active metal supported on a carrier consisting of boria, silica, and alumina with an average pore diameter of 90 to 120 xc3x85 is suitable for obtaining high middle distillate selectivity. Thus, improving middle distillate selectivity by taking into consideration the pore diameter distribution of so-called mesopores is a technology that is known in this field.
On the other hand, hydrocracking catalysts that are packed in fixed bed reactors and used industrially are usually shaped into cylinders or spheres. Technology where there are so-called macropores of 0.05 xcexcm or larger present in this type of shaped catalyst is also known. For example, Japanese Patent Publication No. 05-36099 discloses a catalyst obtained by supporting hydrogenation active component on a carrier consisting of an alumna inorganic oxide and zeolite in order to hydrogenate mainly heavy hydrocarbons such as atmospheric residue. This Japanese Patent Application Laid Open discloses the fact that because this catalyst has macropores with a pore diameter of 600 xc3x85 or larger at 0.1 mL/g or more, deposition of carbonaceous matter and metal impurities and plugging of pores caused by the deposition can be prevented and as a result, yield of the kerosene and gas oil is improved.
Nevertheless, in general, shaped catalysts with macropores generally have a disadvantage in that their mechanical strength is weak because porosity is high (Takabo Shirozaki, Takayuki Todo, editors, xe2x80x9cCatalyst Preparation,xe2x80x9d Kodansha, 1974) and therefore, the problem easily develops where the catalyst is broken down and crushed when catalyst is produced and packed in the reactor or during the reaction.
To the inventors"" knowledge, there is still no technology whereby a hydrocracking catalyst is simultaneously given a specific mesopore diameter distribution and a specific macropore diameter distribution and the hydrocracking catalyst is used for hydrocracking of hydrocarbon oils, preferably demetalized hydrocarbon oils that mainly contain fractions with boiling points which is higher than a predetermined boiling point, particularly vacuum gas oil or heavy gas oil.
The purpose of the present invention is to provide a new hydrocracking catalyst with a high conversion rate and middle distillate selectivity in hydrocracking of hydrocarbon oils, particularly vacuum gas oil and heavy gas oil, and practical mechanical strength, and to provide a method of producing this catalyst as well as a method of hydrocracking using this hydrocracking catalyst.
The hydrocracking catalyst of the present invention is provided, which comprises a catalyst carrier having particles of a compound oxide and a binder component present between these particles, and at least one metal component selected from Group 6(VI), Group 9(IX) and Group 10(X) of the Periodic Table, wherein
(A) the median pore diameter of the catalyst is 40 to 100 xc3x85 and the volume of pores whose pore diameter is within a range of 40 to 100 xc3x85 is at least 0.1 mL/g and
(B) the volume of pores whose pore diameter is within a range of 0.05 to 0.5 xcexcm of the catalyst is 0.05 to 0.5 mL/g and the volume of pores with a pore diameter of 0.5 to 10 xcexcm is less than 0.05 mL/g.
The compound oxide is preferably made up of one or more selected from silica-alumina, silica-titania, silica-zirconia, silica-magnesia, silica-alumina-titania, and silica-alumina-zirconia. Also, the compound oxide is preferably made up of one or more selected from silica-alumina, silica-titania, silica-zirconia, silica-magnesia, silica-alumina-titania, and silica-alumina-zirconia; and USY zeolite.
Moreover, the binder component is made from alumina and/or boria-alumina, and the metal component is preferably one or more of molybdenum, tungsten, cobalt, rhodium, iridium, nickel, palladium, and platinum, and furthermore, it is preferred that at least 60% of the compound oxide particles have a diameter of 10 xcexcm or smaller.
The method of producing a hydrocracking catalyst (hydrocracking catalyst composition) of the present invention comprises the steps of mixing compound oxide powder comprising at least 60% powder with a particle diameter of 10 xcexcm or smaller and binder component; shaping, drying and firing the mixture to form the carrier; and supporting at least one metal component selected from Group 6, Group 9 and Group 10 of the Periodic Table on the carrier, and thereby obtaining a hydrocracking catalyst wherein (A) median pore diameter is 40 to 100 xc3x85 and the volume of pores whose pore diameter is within a range of 40 to 100 xc3x85 is at least 0.1 mL/g and (B) volume of pores whose pore diameter is within a range of 0.05 to 0.5 xcexcm is 0.05 to 0.5 mL/g and volume of pores with a pore diameter of 0.5 to 10 xcexcm is less than 0.05 mL/g.
By means of the above-mentioned production method, the binder component is made from one or more selected from hydrated aluminium oxide or boria-containing hydrated aluminium oxide.
The method of hydrocracking hydrocarbon oils in accordance with the present invention is a method with which hydrocarbon oils can be converted to a product in which the fraction with a relatively high boiling point contained in this hydrocarbon oil has been reduced by bringing the hydrocarbon oil into contact with the above-mentioned hydrocracking catalyst of the present invention in the presence of hydrogen.